Interestingly, the spectrum of SN 2010lp shows clear Na i D interstellar
absorption lines. A Galactic component has equivalent width EW(Na i D)\(_{\rm Gal}=0.69\)  Å, while the component at the redshift of the host galaxy
(\(z=0.010\) ) has EW(Na i D)\(_{\rm host}=0.35\)  Å. Since Galactic reddening is
E(B–V)\(_{\rm Gal}=0.094\)  mag [1]} using the same relation between
EW(Na i D) and E(B–V) as in the Galaxy (E(B–V) / EW(Na i D)\( =0.136\)  mag Å\(^{-1}\) ), we obtain E(B–V)\(_{\rm host}=0.048\)  mag. This is
intermediate between the values derived using two empirical relations between
EW(Na i D) and reddening. One, presented by [2]}, gives E(B-V)\(_{\rm host}=0.056\)  mag, while the other, proposed by [3]}, yields
E(B–V)\(_{\rm host}=0.036\)  mag. These relations are subject to a large
uncertainty [4]}, such that we may estimate E(B–V)\(_{\rm host}=0.048 \pm 0.012\)  mag. The total reddening towards SN 2010lp is then
E(B-V)\(_{\rm tot}=0.14 \pm 0.01\)  mag. When the spectrum of SN 2010lp is
dereddened by this amount, both the continuum and line features look very
similar to the spectrum of SN 1991bg.
